MIC2589/2595
Micrel
Pin Description
Pin Number
Pin Name
PWRGD1
(MIC25XX-1)
Active-High
1
/PWRGD1
(MIC25XX-2)
Active-Low
2
PGTIMER
Pin Function
Power-Good Output 1: Asserted when the voltage on the DRAIN pin
(V
DRAIN
) is within V
PGTH
of VEE, indicating that the output voltage is within
proper specifications. For the MIC2589-1 and MIC2985-1, PWRGD1 will be
high impedance when V
DRAIN
is less than V
PGTH
, and will pull-down to
V
DRAIN
when V
DRAIN
is greater than V
PGTH
. For the MIC2589-2 and
MIC2595-2, /PWRGD1 will pull-down to V
DRAIN
when V
DRAIN
is less than
V
PGTH
, and will be high-impedance when V
DRAIN
is greater than V
PGTH
.
A capacitor connected from this pin to VEE sets the time interval between
assertions of PWRGD2 (or /PWRGD2) and PWRGD3 (or /PWRGD3)
relative to PWRGD1 (or /PWRGD1). See the “Functional Description” for
further detail.
MIC2589 and MIC2589R: Undervoltage Threshold Input. When the voltage
at the UV pin is less than the V
UVL
threshold, the GATE pin is immediately
pulled low by an internal 100µA current pull-down. The UV pin is also used
to cycle the device off and on to reset the circuit breaker. Taken together,
the OV and UV pins form a window comparator which define the limits of
V
EE
within which the load may safely be powered.
MIC2595 and MIC2595R: Turn-Off Threshold. When the voltage at the OFF
pin is less than the V
OFFL
threshold, the GATE pin is immediately pulled
low by an internal 100µA current pull-down. The OFF pin is also used to cycle
the device off and on to reset the circuit breaker. Taken together, the ON
and OFF pins provide programmable hysteresis for the MIC2595 to be
enabled.
MIC2589 and MIC2589R: Overvoltage Threshold Input. When the voltage
at the OV pin is greater than the V
OVH
threshold, the GATE pin is immediately
pulled low by an internal 100µA current pull-down.
MIC2595 and MIC2595R: Turn-On Threshold. At initial system power-up or
after the part has been shut off by the OFF pin, the voltage on the ON pin
must be above the V
ONH
threshold in order for the MIC2595 to be enabled.
Current Limit Response Timer: A capacitor connected between this pin and
VEE provides filtering against nuisance tripping of the circuit breaker by
setting a time delay, t
FLT
, for which an overcurrent event must last prior to
signaling a fault condition and latching the output off. The minimum time for
t
FLT
will be the time it takes for the output (capacitance) to charge to V
EE
during start-up. This pin is held to VEE with a 3µA current pull-down when
no current limit condition exists. See the “Functional Description” for further
details.
No-Load Detect Timer: A capacitor between this pin and VEE sets the
interval, t
NLD
, for which the current through the external MOSFET can drop
below 10% of full-scale current limit before the circuit breaker is tripped.
Tying this pin to V
EE
will disable this function. This pin is held to VEE by an
internal NMOS when there is no undercurrent condition.
Negative Supply Voltage Input.
No Internal Connection.
Circuit Breaker Sense Input: A resistor between this pin and VEE sets the
current limit trip point for the circuit. When the current limit threshold of IR =
50mV is exceeded for t
FLT
, the circuit breaker is tripped and the GATE pin is
immediately pulled low. Toggling UV or OV will reset the circuit breaker. To
disable the circuit breaker, externally tie SENSE and VEE can be connected
together.
Gate Drive Output: Connects to the Gate of an N-Channel MOSFET.
Drain Sense Input: Connects to the Drain of an N-Channel MOSFET.
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3
UV
Threshold
3
OFF
(Turn-Off Threshold)
4
OV
Threshold
ON
(Turn-On Threshold)
CFILTER
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4
5
6
CNLD
7
8
9
VEE
NC
SENSE
10
11
GATE
DRAIN
March 2004
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3
M9999-031504
MICREL [ MICREL SEMICONDUCTOR ]
